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The Open and Closed Exercise Debate

Injury to the anterior cruciate ligament (ACL) of the knee has become common, especially in athletes. Rehabilitation after ACL surgery is especially important for athletes, since they put heavier demands on their injured knees. Rehabilitation professionals are currently debating whether open or closed chain kinetic exercises are best for people after ACL surgery. In open kinetic chain exercise, the leg is free to move in various directions. In closed kinetic chain exercise, the leg is fixed to a surface as the joints closer to the body work.

Recent evidence has suggested that closed chain exercises are safer and have better results after ACL reconstruction. But very little research has been done to directly compare the two types of exercises. These authors followed 37 patients through four weeks of therapy following ACL surgery. The patients were divided into two groups. One group did open kinetic chain exercises as part of their standard physical therapy. They used ankle weights or knee and hip extension machines. The other group did closed chain exercises on a leg press machine. (Squats are the closed chain exercise normally used in rehabilitation, but the injured leg needed to be exercised alone for the purposes of this study.) Both groups did the special exercises only for their affected knee.

Researchers studied the gait, or walking motions, of the patients to see how physical therapy affected their knees. Researchers measured the movements of the knee joint while walking, going up stairs, and coming down stairs. The gait studies were done two and six weeks after surgery. In between gait studies, the patients saw a physical therapist three times a week.

The injured knees in both groups improved significantly over the course of the study. Researchers saw very little difference between the two groups. However, they did see some extra improvement in the stair climbing mechanics of the group who did open chain exercises. The difference was small, however. The patients may not have noticed any difference.

The findings of this study reopen the argument on open versus closed chain exercises. But the authors caution that more research is needed before a winner is declared in this ongoing debate. There is a need to better understand how open and closed chain exercises affect a knee after ACL reconstruction surgery.

References: David M. Hooper, PhD, et al. Open and Closed Kinetic Chain Exercises in the Early Period After Anterior Cruciate Ligament Reconstruction: Improvements in Level Walking, Stair Ascent, and Stair Descent. In The American Journal of Sports Medicine. March/April 2001. Vol. 29. No. 2. Pp. 167-174.

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